We discuss about ultra-sensitive infrared spectroscopic techniques enhanced by metamaterials. To suppress unwanted background and noises in IR spectroscopy, metamaterial absorber with three-dimensional vertical-oriented metal-insulator-metal (v-MIM) structure was introduced. Owing to small footprint of v-MIM, the density of hot spots was dramatically increased resulting in strong signal enhancement and efficient suppression of background light. Using this device, 20 ppm concentration of carbon dioxide and butane molecules were detected. In addition, metamaterial reflector made of all dielectric structure were also investigated. The dielectric metasurfaces consisting of silicon microdisk arrays were designed and fabricated, realizing perfect reflection at certain mid-infrared wavelengths.
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